1. Field of the Invention
The present invention relates to a backlight module, and in particular to a backlight module that comprises elastic bodies to retain a light guide board.
2. The Related Arts
Liquid crystal display (LCD) has a variety of advantages, such as compact device size, low power consumption, and being free of radiation, and is thus widely used. Most of the LCDs that are currently available in the market are backlighting LCDs, which comprise a liquid crystal display panel and a backlight module. The working principle of the liquid crystal display panel is that liquid crystal molecules interposed between two parallel glass plates and a plurality of vertical and horizontal fine electrical wires is arranged between the two glass plates, whereby the liquid crystal molecules are controlled to change direction by application of electricity to refract light emitting from the backlight module for generating images. Since the liquid crystal display panel itself does not emit light, light must be provided by the backlight module in order to generate images. Thus, the backlight module is one of the key components of an LCD. The backlight module can be classified as two types, namely side-edge backlight module and direct backlight module, according to the position where light gets incident. The direct backlight module arranges a light source, such as a cold cathode fluorescent lamp (CCFL) or a light-emitting diode (LED) at the back side of the liquid crystal display panel to form a planar light source to directly provide lighting to the liquid crystal display panel. The side-edge backlight module arranged an LED light bar of light source at an edge of a back panel that is located rearward of one side of the liquid crystal display panel. The LED light bar emits light that enters a light guide plate through a light incident face of the light guide plate and is projected out through a light exit face after being reflected and diffused to thereby form a planar light source to be provided to the liquid crystal display panel.
In the manufacture process of backlight module, positioning and retaining a light guide board is very important. The conventional way of positioning and retaining a light guide board is to provide rivet pegs on a backplane or to make bending to form retention pawl structures and to form corresponding slots or projections on the light guide board in order to effect to engagement and positioning. However, the current trend of LCD is thinning and increasing size. This makes the light guide board increasingly thin and the thermal expansion characteristics of the light guide board due to absorption of heat are getting prominent. This makes it necessary, in mounting a light guide board, to keep a gap between a positioning section of the light guide board and an engagement and mounting structure of the backplane for accommodating expansion and contraction of the light guide so that the light guide board is provided with a predetermined amount of movability in the interior of the backlight module. The movement of the light guide board may easily lead to problems, such as abrasion of the light guide board. Further, since the light guide board comprises slot or projection structures, the manufacture cost is increased and the mechanical strength of the light guide board is reduced, so that breaking may occur on the light guide board when subjected to impacts caused by external forces. Further, since the light guide board is provided in a circumference thereof with slot or projection, the optic path of light might get locally varied at the sides of the light guide board and this may cause certain optic problems, such as non-uniform brightness at edges of the backlight module, making the yield rate of slim bezel backlight module significantly reduced.